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After spending 1,000 days on the Martian surface, NASA’s Perseverance rover has revealed new details about the history of ancient lake and river deltas on the red planet.
The new insights, which can be detected thanks to the rover’s ground details, are helping scientists piece together the answer to the mysterious history of Mars, and ultimately they could determine if life ever existed there.
Perseverance and its companion helicopter, Ingenuity, landed in Jezero Crater on February 18, 2021, to search for signs of ancient microbial life.
As part of the search, the robotic probe completed its investigation of a river delta that once fed into a lake that filled Jezero Crater billions of years ago. Along the way, Persistence has also collected 23 rock samples from various locations throughout the crater and delta.
Each sample, about the size of classroom chalk and encased in metal tubes, may be returned to Earth in the future by NASA and the European Space Agency’s joint Mars Sample Return campaign. If the samples were studied on Earth, a more detailed analysis would be possible using laboratory equipment that would be too expensive to send to Mars on board the rover.
Scientists shared some of the insights they gained from Perseverance’s journey across Mars on Tuesday at the fall meeting of the American Geophysical Union in San Francisco.
After the water on Mars
The rover collects samples by using a scraping tool on its arm to scratch at Martian rock surfaces and then analyzes the rock’s composition using its Planetary Instrument for X-ray Lithochemistry, called PIXL.
Some of Perseverance’s recent rock samples include silica, a fine-grained mineral that helps preserve ancient fossils and organic molecules on Earth. Organic molecules can be formed during geological and biological processes.
“On Earth, you often find this fine-grained silica in a setting that was once sandy,” Morgan Cable, PIXL’s deputy principal investigator at NASA’s Jet Propulsion Laboratory in Pasadena, California, said in a statement. “It’s the kind of environment where, on Earth, remnants of ancient life could be preserved and later found.”
Some of the rocks also contained iron associated with phosphate, a natural source of the element phosphorus that functions as a component of DNA and cell membranes.
Carbonate was also detected in the samples. These minerals represent past water-rich environments, acting like time capsules for the environmental conditions on Mars from when the rocks first formed.
“We chose Jezero Crater as a landing site because orbital imagery showed a delta – clear evidence that the crater was once filled with a large lake. A lake is a potentially habitable environment, and delta rocks are a great environment to absorb signs of ancient life as fossils in the geologic record,” said Ken Farley, Persistence project scientist and professor of geochemistry at the California Institute of Technology. in a statement. “After a thorough investigation, we have pieced together the geological history of the crater, tracing the course of the lake and river from beginning to end.”
Martian rocks tell a story
Scientists believe that Jezero Crater was formed when an asteroid crashed into Mars 4 billion years ago.
The persistence of his mission began by studying and sampling the crater floor soon after landing. The rover’s detective work helped scientists determine that the crater floor is made of volcanic rock formed by magma that rose to the surface or volcanic activity on the Martian surface.
As Persistence progressed, the rover encountered samples of sandstone and mudstone, suggesting that a river flowed into the crater millions of years after it formed. A top layer of salt-rich mudstones is what remains to show that the crater, which reached 22 miles (35 kilometers) wide and 100 feet (30 meters) deep, was filled by a shallow lake before climate change on the lake.
Persistence also found evidence of boulders that came from other parts of Mars and were deposited within the delta and in the creature by fast-flowing rivers.
“We were able to see a broad outline of these chapters in Jezero’s history in orbital images, but we needed to touch Persistence to understand the timeline in detail,” said Libby Ives, a postdoctoral fellow at the Laboratory NASA Propulsion Jet, i. statement.
Perseverance’s suite of instruments has the ability to detect microscopic fossil structures and the chemical trails left behind by microbial life, but the rover detected neither. However, the geological evidence collected by the rover so far is a tantalizing picture.
“We have great conditions to find signs of ancient life where we find carbonates and phosphates, which indicate a habitable aquatic environment, as well as silica, which is great for preservation,” said Cábla.
And the mission is not over yet. Next, the rover will study an area near the crater entrance where a river flooded across the crater floor, leaving behind carbonate deposits that resemble a bathtub ring.
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